Can a magnet's magnetic field perform work on another magnet?

[Q-reeus]

And your continued iniability to produce any evidence suppporting your objectionable claims bears out my assessment of your bias and ignorance. Your beliefs are unsupported by and uninfluenced by evidence.

It isn't up to me to answer every nonsense objection you raise when you cannot even demonstrate that the topic is a valid concern. If YOU think that there is something wrong with some aspect of classical mechanics, then it is up to YOU to show good evidence why. I won't waste time attacking your half-baked whimsical speculations.

What you see as ego is simply a resistance on my part to accept your unsubstantiated claims which contradict the good evidence that I currently have available to me. Simply look at my interactions with others who have provided good evidence to support their claims which contradicted mine.

That kind of polemic reads like a de facto admission of having no real answers.

Btw, I have lost track of which issue in 49 is the one that you were particularly concerned about?

The first one there, as if you didn't know. Try 'Planck scale'.

I don't know why. In every theory of matter, including the standard model, there are properties of the matter that are determined only by experiment and not by the theory. Why should it be OK for QED to experimentally determine the charge of an electron but not OK for classical EM to experimentally determine the constituitive relationship for a ferromagnet? I am not claiming that classical EM is a theory of everything, merely that it accurately describes the work done when one ferromagnet interacts with another.

You specifically maintain that work on permanent magnets is not just mostly (which it isn't), but exclusively of the actual E.j type, yet continually shy away from defending it against my counterclaims, as I have continually asked.

Q-reeus: "Classical perfectly conducting loop currents are drastically different in behavior to real intrinsic magnetic moments. Face up to that, and your position crumbles."

How does my position crumble? I have never taken the position that classical ferromagnets are modeled as loop currents in a perfecly conducting material. That was your strawman position, and I have already agreed that the strawman position is wrong, but it was never my position.

There are only three possible models to use for magnetized media (ignoring for the moment eddy currents which are peripheral):
Gilbert model based on magnetic monopoles formed into rigid dipoles
Classical Amperian loop currents which have to be perfectly conducting
Intrinsic magnetic moments. [better not forget orbital contribution - significant only in ferrites. And which behave very much as for intrinsic moments, and far from classical Amperian currents.]

Once you accept that only the latter fits the facts, your whole position crumbles as stated.

Q-reeus: "And just what kind of 'evidence' do you need here?"
I need a rigorous derivation from accepted laws of physics, or reliable experimental evidence by reference from mainstream scientific literature. That should always be considered an acceptable request on this forum.

The only reliable experimental evidence needed in this instance is the fact of magnetic saturation. Supplemented with a head that can think independently.

 

[Dale]

That kind of polemic reads like a de facto admission of having no real answers.

Your inability to produce any evidence reads like a de facto admission of having no real question. It doesn't bother me in the slightest that I have no real answer to no real question.

You specifically maintain that work on permanent magnets is not just mostly (which it isn't), but exclusively of the actual E.j type, yet continually shy away from defending it against my counterclaims, as I have continually asked.

I have provided evidence supporting my position in the form of references to rigorous derivations from accepted laws of physics. Why should I defend against your counterclaims when there is no evidence to support them?

The first one there, as if you didn't know. Try 'Planck scale'.

What is wrong with that? Whenever you are calculating some quantized observable there is always a factor involving Planck's constant, the Planck scale I am referring to. If any of your energies/masses/sizes etc. are small compared to the appropriate Planck-scale factor then quantum effects are important, if they are all large compared to the factor then quantum effects are not important.

The only reliable experimental evidence needed in this instance is the fact of magnetic saturation. Supplemented with a head that can think independently.

The constituitive relationships for ferromagnets include magnetic saturation also, so that is not evidence against the applicability of classical EM here. I can post a link later if you need a reference.

 

[Q-reeus]

Hehe I'm reasonable - and of course a clarification is reasonable.

Good show. Reasonableness in a thoroughly unreasonable thread is a welcome relief.

I summarized the cases that I analysed in post #216 again in post #228.

With "a real magnet" I was referring to my conclusion from case 2, permanent magnets without iron (permanent=without external current source). On purpose I kept it simple, avoiding complications by magnetization etc. And indeed I took it for granted that if the magnetic field of a permanent magnet without iron can do work, this will also be valid for magnets with iron.

OK having now looked at what you are saying in the light of #228, I both agree and disagree with that position. Agreed that for permanent magnets the energy exchanges are necessarily of magnetic nature so in that sense the magnetic field is doing the work. Disagree though that this can be modeled using zero resistance loop currents. Such currents must respect Lenz's law and that always means diamagnetism, not the observed ferromagnetism. The latter is dominated by contribution from intrinsic moments - which never change magnitude - only orientation under action of magnetic fields. Not agreeing?

 

[Q-reeus]

Q-reeus: "That kind of polemic reads like a de facto admission of having no real answers."
Your inability to produce any evidence reads like a de facto admission of having no real question. It doesn't bother me in the slightest that I have no real answer to no real question.

If you do decide to quit this tit-for-tat nonsense, think about a serious response to just one question. How can E.j type work be performed on an intrinsic magnetic moment. Answer in your own words.

Q-reeus: "The first one there, as if you didn't know. Try 'Planck scale'."

What is wrong with that? Whenever you are calculating some quantized observable there is always a factor involving Planck's constant, the Planck scale I am referring to. If any of your energies/masses/sizes etc. are small compared to the appropriate Planck-scale factor then quantum effects are important, if they are all large compared to the factor then quantum effects are not important.

Still wishing to maintain correctness? Just read the very first sentence here: http://en.wikipedia.org/wiki/Planck_scale

The constituitive relationships for ferromagnets include magnetic saturation also, so that is not evidence against the applicability of classical EM here.

It is if you understand the issue - your claim exclusively (or even substantially) real E.j work is done on permanent magnets. Bunk.

 

[harrylin]

[..] Agreed that for permanent magnets the energy exchanges are necessarily of magnetic nature so in that sense the magnetic field is doing the work.

Nice to finally get a response of my example.

Disagree though that this can be modeled using zero resistance loop currents. [..]

I thought to use the Ampere model of permanent magnets: https://en.wikipedia.org/wiki/Force_between_magnets#Amp.C3.A8re_model
According to you this does not lead to an erroneous answer to the question, and that's what matters.
However, if you think to offer a better classical model, please redo the analysis with it.

PS: I rephrased this message to highlight the essentials when Q-reeus replied.

 

[Q-reeus]

I thought to use the Ampere model of permanent magnets: https://en.wikipedia.org/wiki/Force_...C3.A8re_model

And here's the part from that link that matters re Ampere model:

That is why Ampere per meter is the correct unit of magnetism, even though these small current loops are not really present in a permanent magnet.

The validity of Ampere's model means that it is allowable to think of the magnetic material as if it consists of current-loops, and the total effect is the sum of the effect of each current-loop, and so the magnetic effect of a real magnet can be computed as the sum of magnetic effects of tiny pieces of magnetic material that are at a distance

[emphasis added]This is is in reference to the field generated by a fixed magnet - assuming such tiny loop currents have their currents sustained against any perturbation. It's a convenient fiction but ignores the fundamental problem of how such zero resistance loops can be assembled to form a magnet in the first place, or how if such a miracle of technology were possible, subsequent diamagnetism in respect of Lenz's law could be avoided. Intrinsic moments suffer no such problems.

If you hold that a current loop is not a valid model for determining if a permanent magnet does work in classical mechanics, please replace it by a model that you do accept and redo the analysis.

Intrinsic moments. Easy. Well, fine details are complicated, but essentially, one cannot explain permanent magnetism, especially ferromagnetism, via classical loop currents. Your magnetic force formulas are then apt - just don't yield to the pressure here to apply double accounting by supposing the purely formal E.j 'work' done on those fictitious Amperian currents is real. It aint.

 

[Dale]

If you do decide to quit this tit-for-tat nonsense, think about a serious response to just one question. How can E.j type work be performed on an intrinsic magnetic moment. Answer in your own words.

Because the laws of classical EM require all EM work to be of the "E.j type". As proven already.

Still wishing to maintain correctness? Just read the very first sentence here: http://en.wikipedia.org/wiki/Planck_scale

Hmm. That is definitely not what I meant. Then I don't know the word to describe the energy/mass scale at which quantum effects become important. Hopefully with my earlier description of the factors containing Planck's constant my meaning is clear. I do apologize for using terminology that already had another meaning which was different from the meaning I intended to convey.

It is if you understand the issue - your claim exclusively (or even substantially) real E.j work is done on permanent magnets. Bunk.

The best way to de-bunk a claim is to provide good evidence. The fact that you cannot do so after hundreds of posts indicates the weak and speculative nature of your argument.

 

[cabraham]

Wow, this thread is still going? I thought we exhausted the case. Every relevant fact, to the best of my knowledge, has been presented. This case should be closed.

Like all EE/scientist types, I believe that any issue can be endlessly debated. Our job is not to argue, but define things in a logical productive manner so that info can be conveyed with as little ambiguity as possible. So why is there conflict over work?

I can only echo what other very capable people have already stated in this thread. How do we define exactly which entity is really "doing the work". The tractor/rope example was relevant. If a tractor is moving, with a rope attached, which lifts something out of a well, what did the work?

We have to define what we consider our "system", & which forces enter our defined system. If the system is confined to the space immediately around the object ascending from the well, then the rope did the work. But the tractor did work on the rope if we consider the system extended outside said rope. The rope transmits the force which lifts the object.

The IC engine in the tractor is doing work as well. Is this part of our defined system? You tell me.

E.J is definitely a quantity describing energy transfer. But where does it transfer? The next entity which receives this energy also transfers all or part of it. Arguing as to whether Fm (magnetic part of Lorentz force) or Fe (electric part) "does the work" is like arguing whether the tractor or the rope does the work lifting object out of well.

It is too apparent to me, some will differ, that Fm, the Lorentz force component associated with B (magnetic) can definitely do work. But can it do so w/o E.J? Of course not. Those who argue that the rope is not lifting or doing work, but merely acting as a channel for the tractor to do so, can make that claim with some validity. It depends on how you define your system boundaries.

If we examine the lower magnet, & the system is defined as the space just outside said magnet, then the Fm force does the work (magnetic), just as the rope dos the work lifting the object from the well. But a broader system boundary will show that the B field is energized by another entity which can be said to be "doing work". For an electromagnet, the power source is doing the work in a broad sense.

But if we extend the system boundaries, we know that the power plant turbine is doing the work. Well, actually, the coal being burned is doing the work. How far do we take this?

I believe that the people who demonstrated how magnetic forces do the work have proved their case beyond a doubt. The naysayers have not disproved them, they just drew the system boundaries differently, & shown how another entity energized said B field which lifted the magnet. So in their narrow view, said entity transferring energy to B field is what "really did the work".

Just as the fuel in the IC engine did work propelling the tractor, the tractor did work tugging the rope, & the rope did work lifting the object from the well, a similar scenario exists with magnetic forces.

Fm did work lifting the magnet, but the energy in the B field comes from a source. For an electromagnet we can use E.J, then we can say that E.J transfers to B²/2mu. Of course, the power source (ac mains or vehicle alternator) is what energizes E.J. We can go back to the fuel in the tank or coal at the power plant.

The critics made some correct presentations, but they do not disprove that Fm does work. They just state the source of the B field energy doing the work. They are correct in stating that w/o the power source, or E.J, or whatever, that the magnet won't ascend. But that is so well known, they are not illuminating us with such material.

The critics , OTOH, are totally out to lunch by thinking that the motion of the magnet generates an E field which provides the work. This is rubbish. Causality is turned on its head. This theory was rightfully deep sixed quickly. How anyone can even present such nonsense is embarrassing. Anyway, those are my thoughts, feedback/comments welcome. Cheers.

Claude

 

[Q-reeus]

Because the laws of classical EM require all EM work to be of the "E.j type". As proven already.

As proven imo only for the fully classical situation of conducting circuits interacting with magnetic fields of non ferromagnetic or similar origin. As not proven for the mixed case here where magnets subject to QM rules interact via EM fields governed by the ME's.

Hmm. That is definitely not what I meant. Then I don't know the word to describe the energy/mass scale at which quantum effects become important. Hopefully with my earlier description of the factors containing Planck's constant my meaning is clear. I do apologize for using terminology that already had another meaning which was different from the meaning I intended to convey.

Fine - apology accepted and glad that one's out of the road. For magnetic media the only relevant parameter I can think of is the Curie temperature, but we are assuming magnetizable media well below that value.

The best way to de-bunk a claim is to provide good evidence. The fact that you cannot do so after hundreds of posts indicates the weak and speculative nature of your argument.

Then I guess this is a true stalemate. So be it.

 

[Q-reeus]

Claude - you asked for feedback, so here's mine. I can agree with much of your #248, the central theme evidently being that energy changes are a cooperative phenomenon requiring all parts to participate. You used electromagnets as example where E.j type energy exchanges occur, and that I won't and never have denied. While the OP didn't specify in the title or #1 entry "Can a magnet's magnetic field perform work on another magnet?", it has been generally understood to mean interaction of permanent magnets, for which there are no external power sources. So what is your understanding of where real E.j work is done when permanent magnets (assume fully magnetized) undergo some relative motion resulting in mechanical work? Assume slow motions and high resistivity material.

 

[OmCheeto]

I'm going to go find that professor at Reed College, and grab him by the throat, and make him write in (his own) blood that there are at least two answers to the OP's question...

 

[Q-reeus]

I'm going to go find that professor at Reed College, and grab him by the throat, and make him write in (his own) blood that there are at least two answers to the OP's question...

He he he. Do we all pine for the days of childhood when playing with magnets brought a sense of wonder and awe, if not outright pleasure? How it all changes.

 

[Dale]

E.J is definitely a quantity describing energy transfer.

I think that you and I agree on the physics, just not the semantics. So I respect your position and think it is reasonable.

The critics , OTOH, are totally out to lunch by thinking that the motion of the magnet generates an E field which provides the work. This is rubbish.

This "rubbish" usually goes by the name "Faraday's law of induction".

 

[Dale]

As proven imo only for the fully classical situation of conducting circuits interacting with magnetic fields of non ferromagnetic or similar origin. As not proven for the mixed case here where magnets subject to QM rules interact via EM fields governed by the ME's.

An opinion unsupported by any good evidence, and one not shared by authors of classical EM textbooks, like Jackson.

Yes, this is a stalemate. At least we agree on that.

 

[Q-reeus]

I think that you and I agree on the physics, just not the semantics. So I respect your position and think it is reasonable.

"The critics , OTOH, are totally out to lunch by thinking that the motion of the magnet generates an E field which provides the work. This is rubbish."

This "rubbish" usually goes by the name "Faraday's law of induction".

So this is 'agreement'? Ha ha ha ha ha ha ha ha.

 

[Q-reeus]

An opinion unsupported by any good evidence, and one not shared by authors of classical EM textbooks, like Jackson.

Took a look at Jackson 2nd Ed'n, 6.2 'Energy in the Magnetic Field'. The ab-initio assumption is made work is done on any loop current 'to maintain the current constant' against a changing flux through the circuit. OK for real currents flowing through real conducting circuits, but when made a blanket generalization for magnetic media, a strange position given his familiarity with the QM nature of an intrinsic moment. That same position is then translated holus-bolus into 6.8 where Poynting theorem is derived. Can find no account in between where such a classically behaving circuit is contrasted with that of an intrinsic moment. None. Guess that's why you just kept ducking every request of mine to show how E.j type work can be done on an intrinsic moment - Jackson has nothing to say - ipso-facto - neither then can you. Awe and reverence for authority figures. Often works out as good policy, but not always. Myself and others here have given references on the net, even pointing to some respected authority figures here in PF, that dispute Jackson's approach of it seems treating intrinsic magnetic moments as though needing to be maintained against some induced emf as though a classical circulating current. Ho hum. To each their own guru it seems.

 

[cabraham]

I think that you and I agree on the physics, just not the semantics. So I respect your position and think it is reasonable.

This "rubbish" usually goes by the name "Faraday's law of induction".

My "rubbish" comment was ambiguous, so I will restate it to clarify. A moving magnetic field does generate an E field per Faraday Induction Law. That is not "rubbish" at all. The "rubbish" I was referring to was the theory that said induced E field is what exerts the lifting force on the lower magnet.

When the lower magnet is on the floor about to ascend due to lifting force acting upon it, there is initially no motion, hence no induced E field & force. So the force lifting the magnet cannot be induced E field generated force. That theory is pure rubbish. The lift occurs before the induction, so induction & E force cannot account for the lift. Cause must always precede effect, & there are no exceptions or conditions to that rule.

Once again, after the magnet starts moving, an E field is indeed generated per Faraday's Induction Law, no argument there. That's been known since the mid 19th century. I'm glad we generally agree, & I agree that much of this is semantics. To me, the force lifting the magnet is Fm = qvXB. If we expand the system boundary region, another source energized said B field somewhere in history. That source received its energy from another source earlier. The disagreement truly is semantic. At least we agree on that as well. Best regards.

Claude

 

[Dale]

Took a look at Jackson 2nd Ed'n, 6.2 'Energy in the Magnetic Field'. The ab-initio assumption is made work is done on any loop current 'to maintain the current constant' against a changing flux through the circuit. OK for real currents flowing through real conducting circuits, but when made a blanket generalization for magnetic media, a strange position given his familiarity with the QM nature of an intrinsic moment. That same position is then translated holus-bolus into 6.8 where Poynting theorem is derived. Can find no account in between where such a classically behaving circuit is contrasted with that of an intrinsic moment. None.

You can certainly dispute his editorial choices about what to discuss in his text, but my point is that Jackson (and the authors of all other classical EM textbooks of which I am aware) clearly treats permanent magnets classically. I.e. permanent magnets are part of classical EM.

Guess that's why you just kept ducking every request of mine to show how E.j type work can be done on an intrinsic moment - Jackson has nothing to say - ipso-facto - neither then can you.

I haven't ducked it. I have consistently answered it.

1) Permanent magnets are described by classical EM (ref Jackson)
2) Poynting's theorem follows from the laws of classical EM (ref derivations)
3) Work done on matter is E.j in all classical EM (ref Lorentz force law)
4) Therefore work done on a permanent magnet is E.j

Ho hum. To each their own guru it seems.

I don't particularly have a guru; my opinion is just based on the best evidence I have available and subject to revision as new evidence becomes available. It isn't my fault if your argument doesn't measure up by that standard.

 

[Dale]

My "rubbish" comment was ambiguous, so I will restate it to clarify... The disagreement truly is semantic. At least we agree on that as well.

Thanks for the clarification. Given our previous discussion, I thought that it was probably just something like that.

A moving magnetic field does generate an E field per Faraday Induction Law. That is not "rubbish" at all. The "rubbish" I was referring to was the theory that said induced E field is what exerts the lifting force on the lower magnet.

When the lower magnet is on the floor about to ascend due to lifting force acting upon it, there is initially no motion, hence no induced E field & force. So the force lifting the magnet cannot be induced E field generated force. That theory is pure rubbish. The lift occurs before the induction, so induction & E force cannot account for the lift. Cause must always precede effect, & there are no exceptions or conditions to that rule.

I agree with this. The B field does indeed produce the force. I hope I never said otherwise. It is only the work that I was describing, and that is given by E.j. Whether we say that it was B via E.j or E.j via B is less important (IMO) than that we agree on the amount of work done and the forces involved.

 

[Q-reeus]

I haven't ducked it. I have consistently answered it.

1) Permanent magnets are described by classical EM (ref Jackson)

As I stated earlier, fully true only insofar as they act as sources of EM fields, or respond to such fields - with the important exclusion of E field curl component (re non-action on intrinsic moments). There is no way a permanent magnet could exist if governed solely by classical EM. Surely you don't dispute that.

2) Poynting's theorem follows from the laws of classical EM (ref derivations)

Agreed.

3) Work done on matter is E.j in all classical EM (ref Lorentz force law)

Agreed. But PM's are not 'all classical'.

4) Therefore work done on a permanent magnet is E.j

The inevitable non sequitur. Only in a strictly formal sense - by pretending Amperian 'currents' are real currents. And even then, there are problems. But for the sake of not distracting things further, I will simply agree to a presumed formal but not real E.j type 'work' being done, whereas in fact all appreciable interactions are magnetic in origin for PM's.
The marathon's not yet over.

 

[cabraham]

Thanks for the clarification. Given our previous discussion, I thought that it was probably just something like that.

I agree with this. The B field does indeed produce the force. I hope I never said otherwise. It is only the work that I was describing, and that is given by E.j. Whether we say that it was B via E.j or E.j via B is less important (IMO) than that we agree on the amount of work done and the forces involved.

Once again our agreement is near complete. But how can B produce force which displaces the mass a distance upward increasing its PE, w/o doing the work? That is illogical. So we agree B produces the Fm Lorentz force that lifts the magnet. That Fm force times height raised is the work done. B did the work. But, E.J is needed to energize B. Once again, it all depends where the system boundary is arbitrarily drawn.

I'm satisfied that we have consensus except for the matter of arbitrarily choosing system boundaries, & minor semantics. I just find it surprising that so many critics agree on B providing the force, but not doing the work. How can the force which lifts not be doing the work? Strange it is indeed. Oh well, no use dwelling on it. Cheers.

Claude

 

[Dale]

Once again our agreement is near complete. But how can B produce force which displaces the mass a distance upward increasing its PE, w/o doing the work? That is illogical.

Because B doesn't act on the mass, it acts on the charges which are in motion relative to the mass. The force B exerts on the charges is always perpendicular to their motion, per the Lorentz force law, and therefore does not transfer energy.

I'm satisfied that we have consensus except for the matter of arbitrarily choosing system boundaries, & minor semantics. I just find it surprising that so many critics agree on B providing the force, but not doing the work. How can the force which lifts not be doing the work? Strange it is indeed. Oh well, no use dwelling on it.

I agree that the remaining difference is semantic, but hopefully the Lorentz force law and Poynting's theorem help you understand why other people will describe it differently than you do and perhaps help you understand that the description is reasonable, even though it differs from your own.

 

[Dale]

As I stated earlier, fully true only insofar as they act as sources of EM fields, or respond to such fields - with the important exclusion of E field curl component (re non-action on intrinsic moments).

You did state it earlier, but without evidence.

There is no way a permanent magnet could exist if governed solely by classical EM. Surely you don't dispute that.

Classical EM doesn't purport to be a theory about the existence of magnets, charges, or fields. It is just a theory about their behavior. Classical EM does, in fact, accurately describe the behavior of permanent magnets, including force, energy, work, etc.

Only in a strictly formal sense - by pretending Amperian 'currents' are real currents. And even then, there are problems. But for the sake of not distracting things further, I will simply agree to a presumed formal but not real E.j type 'work' being done, whereas in fact all appreciable interactions are magnetic in origin for PM's.

OK, as long as the equations accurately predict the outcome of experiments, that is sufficiently "real" for me. I try to remain agnostic about everything else.

 

[cabraham]

Because B doesn't act on the mass, it acts on the charges which are in motion relative to the mass. The force B exerts on the charges is always perpendicular to their motion, per the Lorentz force law, and therefore does not transfer energy.

I agree that the remaining difference is semantic, but hopefully the Lorentz force law and Poynting's theorem help you understand why other people will describe it differently than you do and perhaps help you understand that the description is reasonable, even though it differs from your own.

Sorry Dale but you can't have it both ways. The E force is also perpendicular to the magnet motion. Not to the charge, but to the direction the mass is moving. Using your definition, E force cannot do work either because E force is not in line with the magnet's motion. I've explained to the point of exhaustion that the work is done on the mass, not the charges. The Fm force (due to B) acts in the right direction along with the motion, but Fe does not. That "Fm is normal to charge motion & thus cannot do work" argument has been demolished beyond sufficiency. We are well beyond that. I can't believe that that argument is still being invoked. I explained that in my 1st post in the 1st thread.

All my posts are consistent with all known laws of physics. Like I said recently, the reason some differ with me is based on where the system boundaries are arbitrarily drawn. If you zoom in close, just looking at Fm & the magnets, then Fm lifts the magnet & does the work. But zoom your lens out to a bigger picture, & B gets energy from another field/source. Zoom out more & another energy source is "doing the work".

Fm acts on the magnet lifting it a finite distance. The Fm direction is along the motion. It does work, not on the charges but on the magnet mass as a whole. The direction is along, not normal. By the definition you cited, that is work being done by Fm (associated Lorentz force per B).

To me it's too easy, & I am at a loss to understand how this can even be argued. We arrived at the right answer long ago. Some just refuse to accept Fm as doing work. It's just a prejudice & nothing more. All attempts to invoke physics laws to prove that E does the work have not withstood scrutiny. BR.

Claude

 

[Dale]

Sorry Dale but you can't have it both ways. The E force is also perpendicular to the magnet motion.

The E field is not perpendicular to the current, therefore it does work on the charges.

I've explained to the point of exhaustion that the work is done on the mass, not the charges.

This is where we disagree. EM forces only act on charges, not masses. I don't know if this is just another semantic disagreement or not, but if it is not then your position seems problematic to say the least.

 

[harrylin]

So this is 'agreement'? Ha ha ha ha ha ha ha ha.

As I already gave up on this topic, seeing all this I just have to laugh along with you - but in despair :

Once again our agreement is near complete. But how can B produce force which displaces the mass a distance upward increasing its P[otential] E[nergy], w/o doing the work? That is illogical. [..]

[..] The force B [..] does not transfer energy. [..] I agree that the remaining difference is semantic [..].

 

[Q-reeus]

As I already gave up on this topic, seeing all this I just have to laugh along with you - but in despair :

Ha ha. Harald, we all agree magnets just keep on working regardless of how each see's it. Guess that's all that really matters in the end.

 

[Miyz]

People! Why can't you all agree that the magnetic fields induce the force that does the work. Call it what you want, but the magnetic field generated a force.

I still don't understand why we haven't finished this yet.

Based on all the laws of Electrodynamics its known as a fact that magnetic fields induce electrical fields and that electrical fields INDUCE magnetic fields. As Claude said before they are of the same coin. Each facing a different side.

They are both equal to each other. In what way? In a way that without one of them, the other can't exist or do anything!

Peace!

Miyze,

 

[cabraham]

People! Why can't you all agree that the magnetic fields induce the force that does the work. Call it what you want, but the magnetic field generated a force.

I still don't understand why we haven't finished this yet.

Based on all the laws of Electrodynamics its known as a fact that magnetic fields induce electrical fields and that electrical fields INDUCE magnetic fields. As Claude said before they are of the same coin. Each facing a different side.

They are both equal to each other. In what way? In a way that without one of them, the other can't exist or do anything!

Peace!

Miyze,

Very true indeed. E & B (or E & H if you like) cannot exist independently if the energy is time varying (power is non-zero). Ampere's Law (AL) tells us that the curl of H equals the displacement current plus the conduction current. The displacement current is dD/dt, & the conduction current is J = σE As we know, D = εE. In a conductor we have conduction current, in an insulator we have displacement current. In either case, E is non-zero if H has a curl. If H is zero, so is E.

Faraday's Law (FL) tells us that the curl of E equals the time rate of change of B. A static B has no E, & an ir-rotational E has no B. But in these cases we've examined, induced E fields are always rotational, hence there has to be a time varying B associated. The B fields enclose a current, hence an E field is present. E forces align with charge carrier velocity.

So whenever one says, this field is "doing the work", another can counter with "no way, the other field is doing it", then produce equations showing how the work cannot be done without the other. They are right, of course, but they don't acknowledge the chicken-egg paradox they are falling victim to. Which comes first is endless.

Fe = qE acts in the wrong direction to lift the magnet, & it cannot be the one doing work. Fm = qvXB is in the right direction lifting the magnet, doing work equal to mgh. Although the Fm is not doing work on charges, it deflects charges w/o changing their KE, & internal bonding forces yank the lattice particles in the direction of the displaced electrons. These forces are E & SN.

I covered this issue in the current loop thread. I was told that my tethering treatise was irrelevant. So I am at a point where it is pointless to continue. I will clarify if asked, but if not asked, then I bid all of you a great & happy weekend, enjoy the pro football games, that is what I will be doing. Cheers.

Claude

 

[Miyz]

Very true indeed. E & B (or E & H if you like) cannot exist independently if the energy is time varying (power is non-zero). Ampere's Law (AL) tells us that the curl of H equals the displacement current plus the conduction current. The displacement current is dD/dt, & the conduction current is J = σE As we know, D = εE. In a conductor we have conduction current, in an insulator we have displacement current. In either case, E is non-zero if H has a curl. If H is zero, so is E.

Faraday's Law (FL) tells us that the curl of E equals the time rate of change of B. A static B has no E, & an ir-rotational E has no B. But in these cases we've examined, induced E fields are always rotational, hence there has to be a time varying B associated. The B fields enclose a current, hence an E field is present. E forces align with charge carrier velocity.

So whenever one says, this field is "doing the work", another can counter with "no way, the other field is doing it", then produce equations showing how the work cannot be done without the other. They are right, of course, but they don't acknowledge the chicken-egg paradox they are falling victim to. Which comes first is endless.

Fe = qE acts in the wrong direction to lift the magnet, & it cannot be the one doing work. Fm = qvXB is in the right direction lifting the magnet, doing work equal to mgh. Although the Fm is not doing work on charges, it deflects charges w/o changing their KE, & internal bonding forces yank the lattice particles in the direction of the displaced electrons. These forces are E & SN.

I covered this issue in the current loop thread. I was told that my tethering treatise was irrelevant. So I am at a point where it is pointless to continue. I will clarify if asked, but if not asked, then I bid all of you a great & happy weekend, enjoy the pro football games, that is what I will be doing. Cheers.

Claude

Good words used in good time.

I probably won't enjoy any games or such! I'll self teach my self about the wonders of or physical world.

Take care Claude!